The uncontrolled growth of microorganisms can cause severe problems in industrial water systems. The most common method of controlling microbial growth in industrial water systems has been through the use of biocides. While a wide variety of biocides are available to the water treatment industry improved methods are required to address efficacy economic and environmental concerns. The non-oxidizing biocide tributyl tetradecyl phosphonium chloride has been shown to be effective against a broad range of microorganisms in a wide variety of industrial environments. We report here on the use of tributyl tetradecyl phosphonium chloride in combination with other commonly used industrial water biocides. The combinations show improved performance compared to the individual biocides alone. The improved performance leads to increased cost performance reduced system corrosion and reduced environmental impact of the biocide treatment.